The present invention relates to methods and compositions for prevention and/or treatment of diseases or conditions caused by deficiency in the adult isoform of a given protein, such as occurs in dystrophies or thalassemia and sickle-cell diseases, wherein said methods comprise administering to a patient in need thereof a composition containing NO or at least one compound able to release or induce NO formation in cells, said administration resulting in augmenting or restoring the production of the fetal isoform of said protein. More specifically, the present invention is directed to a method for inhibiting or reversing the switching from production of fetal to adult isoform of a given protein, thus augmenting or restoring the production of said fetal protein in patient in need thereof. In particular, the present invention is directed to a method for controlling the fetal protein switch by administering to a patient in need a composition containing NO or at least one compound able to release or induce NO formation in cells.
It is known that in mammals, and particularly in humans, including those having the genetic mutations cited below, during fetal development, the fetus produces a fetal hemoglobin which comprises, instead of beta-globin proteins, two gamma-globin proteins. At some point during fetal development or infancy, depending on the particular species and individual, there is a so-called “globin switch” whereby the precursors of erythrocytes in the fetus switch from making predominantly gamma-globin to making predominantly beta-globin. Normal adult hemoglobin comprises a molecule with four polypeptide chains, two of which are designated alpha-subunits and two of which are designated beta-subunits. Diseases known as sickle cell syndromes and thalassemia are associated with genetic mutations in the beta-chain of the haemoglobin. Several treatments of beta-thalassemia have been proposed using chelator or polyanionic amine (for a review, see Rund and Rachmilewitz, 2000, Crit. Rev. Oncol. Hematol., 33:105-118). Alternatively, based on the observation that increased levels of fetal gamma-globin ameliorate the severity of sickling disorders, it has been proposed to re-induce the silent fetal gamma-globin gene in affected patient by administering chemotherapeutic agents (such as hydroxyurea and 5-azacytidine), growth factors (erythropoietin), cytosine arabinoside or butyric acid and butyrate derivatives (for review, please refer to Swank and Stamatoyannopoulos, 1998, Cur. Op. Gen. and Dev., 8:366-370; Rund and Rachmilewitz, 2000, Crit. Rev. Oncol. Hematol., 33:105-118). More specifically, works conducted on sickle-cell disease and thalassemia have demonstrated that hydroxyurea and butyrate are able to reactivate the expression of the fetal gene of hemoglobin. This result could, at least in part, be explained by common metabolic phenomena. The urea and Krebs cycles are coupled together and if hydroxy-urea interferes with the urea cycle, it could lead to retro-regulation of the Krebs cycle, which would cause a lower consumption of acetyl-CoA and therefore the formation of ketone bodies such as beta-hydroxybutyrate. Nevertheless, while said type of compounds might ameliorate the clinical conditions in beta-thalassemia patient, these treatments are not yet enough satisfactory in terms of efficiency or toxicity. Thus, there is still a need for an ideal agent which would be one that is readily available, economically affordable, effective and safe even with chronic use.
Similarly, Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are allelic, lethal degenerative muscle genetic diseases wherein mutations in the dystrophin gene on chromosome x result in the absence of dystrophin, a cytoskeletal protein, under the sarcolemmal membrane in skeletal and cardiac muscle (DMD) or in a reduced level and/or in expression of a shorter, internally deleted form of dystrophin (BMD). Moreover, there exists a fetal isoform of dystrophin expressed at the fetal stage, the utrophin. However, Mizuno et al. (1993, J. Neurol. Sci., 119:43-52) have shown that utrophin is found in the muscles in both MD patients and in adult controls indicating that expression of the corresponding utrophin gene is not fully switch off during development. Actually, the difference between fetus and adult utrophin is its localisation: it is no longer found in the sarcolemma of adult tissue where it is replaced by dystrophin, but it still persists in satellite cells, the neuromuscular junctions and the capillaries. More specifically, in normal muscle fibres, utrophin accumulates selectively at the postsynaptic membrane of the neuromuscular junction where its precise physiological role remains to be determined. Several strategies have been envisaged to counteract the effects of dystrophy, including pharmacological treatment with gluco-corticoids, myoblast transplant and gene therapy (De La Porte et al., 1999, Int. Rev. Cytol., 191:99-148). Upregulation of utrophin has also been proposed as a therapeutic approach via increased expression of utrophin. Previous data have shown that utrophin is able to perform the same cell functions as dystrophin and would therefore be able to compensate for the absence of dystrophin (Blake et al., 1996, Brain Pathol., 1:37-47; Campbell and Crosbie, 1996, Nature, 384:308-309; Deconinck et al., 1997, Nature Med., 3:1216-1221; Tinsley et al., 1998, Nature Med., 4:1441-1444). According to said strategy, if utrophin can be systematically extended from the synaptic regions of dystrophic muscle fibres into extrasynaptic compartments, preferably at the sarcolemma level, it may functionally compensate for the lack of dystrophin or related activity, and thus restore muscle functions. Enhanced utrophin production has been previously obtained in regenerating fibres (i.e., in inflammatory conditions; Helliwell et al., 1992, Neuromuscul. Disord., 2:177-184; Mizuno et al., 1993, J. Neurol. Sci., 119:43-52) or by acting on molecules expressed at the neuromuscular junction, i.e., the neural agrin and heregulin (Gramolini et al., 1997, J. Biol. Chem., 272:8117-8120; Gramolini et al., 1998, J. Biol. Chem., 272:736-743). Nevertheless, even based on said up-regulation of utrophin strategy, no safe and effective therapies for these diseases are available at this time. Therefore, the technical problem underlying the present invention is the provision of improved methods and means for inhibiting or reversing the switching from production of fetal to adult isoform of a given protein, thus augmenting or restoring the production of said fetal protein in patient in need thereof, and preferably in augmenting or restoring said production at targeted site. This technical problem is solved by the provision of the embodiments as defined in the claims.